The son of a former slave, Mr. Nickens served as president of the Frederick branch of the NAACP from the early 1970s until he stepped down in 1992. He had joined the civil rights movement years earlier and spoke out on issues ranging from fair housing to the scourges of drugs and violence.

He said he received death threats from the Klan, whose white supremacist activities he helped challenge in court and at rallies. Once, when a Klan grand dragon infiltrated an NAACP meeting and unleashed a diatribe, Mr. Nickens responded calmly: “We are all one people under one flag.”

After the Supreme Court’s 1954 Brown v. Board school desegregation decision, Mr. Nickens helped lead the effort to integrate Frederick High School. In the late 1960s and early ’70s, he worked to integrate public accommodations such as parks and restaurants, said his NAACP colleague Seaven Gordon.

Some of Mr. Nickens’s signal successes came in housing, Gordon said. In the late 1950s, blacks in Frederick were restricted to largely rundown neighborhoods. Through his organizing, Mr. Nickens helped make it possible for blacks to live anywhere they could afford.

“It was through his efforts that that was done,” Gordon said.

Mr. Nickens was often praised for his measured responses to volatile situations.

In 1975, after a series of racial disturbances, Mr. Nickens called for obedience to the law. “To the rebellious black youth of Frederick City,” he wrote in a highly publicized statement, “you’re only hurting the image of all the blacks in all segments of our society.”

Lord Dunmore Nickens was born Aug. 6, 1913, in White Post, Va. His father, who became a minister, had been born into slavery.

Mr. Nickens first experienced racism at age 6, during his family’s move from Virginia to Maryland. He mistakenly entered a train station bathroom labeled “white.” A conductor kicked him.

Mr. Nickens graduated from Frederick’s all-black Lincoln High School. He joined the NAACP in 1934, he once told a Frederick newspaper, because he thought it was his “only outlet to make contact with the white world.”

Mr. Nickens served in the Army in the Pacific during World War II and received decorations that included the Soldier’s Medal. After the war, he worked as a laboratory technician at the Army installation at Fort Detrick. He retired in the early 1970s.

Survivors include his wife of 67 years, Thelma King Nickens of Adamstown, Md.; three sons, Charles Nickens of Hampton, Va., and Ronald Nickens and Gregory Nickens, both of Adamstown; seven grandchildren; nine great-grandchildren; and one great-great-granddaughter.

In 2007, a street in Frederick was named for Mr. Nickens. He had asked city officials to recognize an African American that way — never knowing he would be the honoree.

Emily Langer is a reporter on The Washington Post’s obituaries desk. She has written about national and world leaders, celebrated figures in science and the arts, and heroes from all walks of life.